xref: /titanic_44/usr/src/uts/common/fs/zfs/vdev_disk.c (revision b17f03d7d89b75b69b9b7db22f2316b700e3a5a8)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23  * Copyright (c) 2012 by Delphix. All rights reserved.
24  */
25 
26 #include <sys/zfs_context.h>
27 #include <sys/spa_impl.h>
28 #include <sys/refcount.h>
29 #include <sys/vdev_disk.h>
30 #include <sys/vdev_impl.h>
31 #include <sys/fs/zfs.h>
32 #include <sys/zio.h>
33 #include <sys/sunldi.h>
34 #include <sys/efi_partition.h>
35 #include <sys/fm/fs/zfs.h>
36 
37 /*
38  * Virtual device vector for disks.
39  */
40 
41 extern ldi_ident_t zfs_li;
42 
43 static void
44 vdev_disk_hold(vdev_t *vd)
45 {
46 	ddi_devid_t devid;
47 	char *minor;
48 
49 	ASSERT(spa_config_held(vd->vdev_spa, SCL_STATE, RW_WRITER));
50 
51 	/*
52 	 * We must have a pathname, and it must be absolute.
53 	 */
54 	if (vd->vdev_path == NULL || vd->vdev_path[0] != '/')
55 		return;
56 
57 	/*
58 	 * Only prefetch path and devid info if the device has
59 	 * never been opened.
60 	 */
61 	if (vd->vdev_tsd != NULL)
62 		return;
63 
64 	if (vd->vdev_wholedisk == -1ULL) {
65 		size_t len = strlen(vd->vdev_path) + 3;
66 		char *buf = kmem_alloc(len, KM_SLEEP);
67 
68 		(void) snprintf(buf, len, "%ss0", vd->vdev_path);
69 
70 		(void) ldi_vp_from_name(buf, &vd->vdev_name_vp);
71 		kmem_free(buf, len);
72 	}
73 
74 	if (vd->vdev_name_vp == NULL)
75 		(void) ldi_vp_from_name(vd->vdev_path, &vd->vdev_name_vp);
76 
77 	if (vd->vdev_devid != NULL &&
78 	    ddi_devid_str_decode(vd->vdev_devid, &devid, &minor) == 0) {
79 		(void) ldi_vp_from_devid(devid, minor, &vd->vdev_devid_vp);
80 		ddi_devid_str_free(minor);
81 		ddi_devid_free(devid);
82 	}
83 }
84 
85 static void
86 vdev_disk_rele(vdev_t *vd)
87 {
88 	ASSERT(spa_config_held(vd->vdev_spa, SCL_STATE, RW_WRITER));
89 
90 	if (vd->vdev_name_vp) {
91 		VN_RELE_ASYNC(vd->vdev_name_vp,
92 		    dsl_pool_vnrele_taskq(vd->vdev_spa->spa_dsl_pool));
93 		vd->vdev_name_vp = NULL;
94 	}
95 	if (vd->vdev_devid_vp) {
96 		VN_RELE_ASYNC(vd->vdev_devid_vp,
97 		    dsl_pool_vnrele_taskq(vd->vdev_spa->spa_dsl_pool));
98 		vd->vdev_devid_vp = NULL;
99 	}
100 }
101 
102 static uint64_t
103 vdev_disk_get_space(vdev_t *vd, uint64_t capacity, uint_t blksz)
104 {
105 	ASSERT(vd->vdev_wholedisk);
106 
107 	vdev_disk_t *dvd = vd->vdev_tsd;
108 	dk_efi_t dk_ioc;
109 	efi_gpt_t *efi;
110 	uint64_t avail_space = 0;
111 	int efisize = EFI_LABEL_SIZE * 2;
112 
113 	dk_ioc.dki_data = kmem_alloc(efisize, KM_SLEEP);
114 	dk_ioc.dki_lba = 1;
115 	dk_ioc.dki_length = efisize;
116 	dk_ioc.dki_data_64 = (uint64_t)(uintptr_t)dk_ioc.dki_data;
117 	efi = dk_ioc.dki_data;
118 
119 	if (ldi_ioctl(dvd->vd_lh, DKIOCGETEFI, (intptr_t)&dk_ioc,
120 	    FKIOCTL, kcred, NULL) == 0) {
121 		uint64_t efi_altern_lba = LE_64(efi->efi_gpt_AlternateLBA);
122 
123 		zfs_dbgmsg("vdev %s, capacity %llu, altern lba %llu",
124 		    vd->vdev_path, capacity, efi_altern_lba);
125 		if (capacity > efi_altern_lba)
126 			avail_space = (capacity - efi_altern_lba) * blksz;
127 	}
128 	kmem_free(dk_ioc.dki_data, efisize);
129 	return (avail_space);
130 }
131 
132 static int
133 vdev_disk_open(vdev_t *vd, uint64_t *psize, uint64_t *max_psize,
134     uint64_t *ashift)
135 {
136 	spa_t *spa = vd->vdev_spa;
137 	vdev_disk_t *dvd;
138 	struct dk_minfo_ext dkmext;
139 	int error;
140 	dev_t dev;
141 	int otyp;
142 
143 	/*
144 	 * We must have a pathname, and it must be absolute.
145 	 */
146 	if (vd->vdev_path == NULL || vd->vdev_path[0] != '/') {
147 		vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
148 		return (EINVAL);
149 	}
150 
151 	/*
152 	 * Reopen the device if it's not currently open. Otherwise,
153 	 * just update the physical size of the device.
154 	 */
155 	if (vd->vdev_tsd != NULL) {
156 		ASSERT(vd->vdev_reopening);
157 		dvd = vd->vdev_tsd;
158 		goto skip_open;
159 	}
160 
161 	dvd = vd->vdev_tsd = kmem_zalloc(sizeof (vdev_disk_t), KM_SLEEP);
162 
163 	/*
164 	 * When opening a disk device, we want to preserve the user's original
165 	 * intent.  We always want to open the device by the path the user gave
166 	 * us, even if it is one of multiple paths to the same device.  But we
167 	 * also want to be able to survive disks being removed/recabled.
168 	 * Therefore the sequence of opening devices is:
169 	 *
170 	 * 1. Try opening the device by path.  For legacy pools without the
171 	 *    'whole_disk' property, attempt to fix the path by appending 's0'.
172 	 *
173 	 * 2. If the devid of the device matches the stored value, return
174 	 *    success.
175 	 *
176 	 * 3. Otherwise, the device may have moved.  Try opening the device
177 	 *    by the devid instead.
178 	 */
179 	if (vd->vdev_devid != NULL) {
180 		if (ddi_devid_str_decode(vd->vdev_devid, &dvd->vd_devid,
181 		    &dvd->vd_minor) != 0) {
182 			vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
183 			return (EINVAL);
184 		}
185 	}
186 
187 	error = EINVAL;		/* presume failure */
188 
189 	if (vd->vdev_path != NULL) {
190 		ddi_devid_t devid;
191 
192 		if (vd->vdev_wholedisk == -1ULL) {
193 			size_t len = strlen(vd->vdev_path) + 3;
194 			char *buf = kmem_alloc(len, KM_SLEEP);
195 			ldi_handle_t lh;
196 
197 			(void) snprintf(buf, len, "%ss0", vd->vdev_path);
198 
199 			if (ldi_open_by_name(buf, spa_mode(spa), kcred,
200 			    &lh, zfs_li) == 0) {
201 				spa_strfree(vd->vdev_path);
202 				vd->vdev_path = buf;
203 				vd->vdev_wholedisk = 1ULL;
204 				(void) ldi_close(lh, spa_mode(spa), kcred);
205 			} else {
206 				kmem_free(buf, len);
207 			}
208 		}
209 
210 		error = ldi_open_by_name(vd->vdev_path, spa_mode(spa), kcred,
211 		    &dvd->vd_lh, zfs_li);
212 
213 		/*
214 		 * Compare the devid to the stored value.
215 		 */
216 		if (error == 0 && vd->vdev_devid != NULL &&
217 		    ldi_get_devid(dvd->vd_lh, &devid) == 0) {
218 			if (ddi_devid_compare(devid, dvd->vd_devid) != 0) {
219 				error = EINVAL;
220 				(void) ldi_close(dvd->vd_lh, spa_mode(spa),
221 				    kcred);
222 				dvd->vd_lh = NULL;
223 			}
224 			ddi_devid_free(devid);
225 		}
226 
227 		/*
228 		 * If we succeeded in opening the device, but 'vdev_wholedisk'
229 		 * is not yet set, then this must be a slice.
230 		 */
231 		if (error == 0 && vd->vdev_wholedisk == -1ULL)
232 			vd->vdev_wholedisk = 0;
233 	}
234 
235 	/*
236 	 * If we were unable to open by path, or the devid check fails, open by
237 	 * devid instead.
238 	 */
239 	if (error != 0 && vd->vdev_devid != NULL)
240 		error = ldi_open_by_devid(dvd->vd_devid, dvd->vd_minor,
241 		    spa_mode(spa), kcred, &dvd->vd_lh, zfs_li);
242 
243 	/*
244 	 * If all else fails, then try opening by physical path (if available)
245 	 * or the logical path (if we failed due to the devid check).  While not
246 	 * as reliable as the devid, this will give us something, and the higher
247 	 * level vdev validation will prevent us from opening the wrong device.
248 	 */
249 	if (error) {
250 		if (vd->vdev_physpath != NULL &&
251 		    (dev = ddi_pathname_to_dev_t(vd->vdev_physpath)) != NODEV)
252 			error = ldi_open_by_dev(&dev, OTYP_BLK, spa_mode(spa),
253 			    kcred, &dvd->vd_lh, zfs_li);
254 
255 		/*
256 		 * Note that we don't support the legacy auto-wholedisk support
257 		 * as above.  This hasn't been used in a very long time and we
258 		 * don't need to propagate its oddities to this edge condition.
259 		 */
260 		if (error && vd->vdev_path != NULL)
261 			error = ldi_open_by_name(vd->vdev_path, spa_mode(spa),
262 			    kcred, &dvd->vd_lh, zfs_li);
263 	}
264 
265 	if (error) {
266 		vd->vdev_stat.vs_aux = VDEV_AUX_OPEN_FAILED;
267 		return (error);
268 	}
269 
270 	/*
271 	 * Once a device is opened, verify that the physical device path (if
272 	 * available) is up to date.
273 	 */
274 	if (ldi_get_dev(dvd->vd_lh, &dev) == 0 &&
275 	    ldi_get_otyp(dvd->vd_lh, &otyp) == 0) {
276 		char *physpath, *minorname;
277 
278 		physpath = kmem_alloc(MAXPATHLEN, KM_SLEEP);
279 		minorname = NULL;
280 		if (ddi_dev_pathname(dev, otyp, physpath) == 0 &&
281 		    ldi_get_minor_name(dvd->vd_lh, &minorname) == 0 &&
282 		    (vd->vdev_physpath == NULL ||
283 		    strcmp(vd->vdev_physpath, physpath) != 0)) {
284 			if (vd->vdev_physpath)
285 				spa_strfree(vd->vdev_physpath);
286 			(void) strlcat(physpath, ":", MAXPATHLEN);
287 			(void) strlcat(physpath, minorname, MAXPATHLEN);
288 			vd->vdev_physpath = spa_strdup(physpath);
289 		}
290 		if (minorname)
291 			kmem_free(minorname, strlen(minorname) + 1);
292 		kmem_free(physpath, MAXPATHLEN);
293 	}
294 
295 skip_open:
296 	/*
297 	 * Determine the actual size of the device.
298 	 */
299 	if (ldi_get_size(dvd->vd_lh, psize) != 0) {
300 		vd->vdev_stat.vs_aux = VDEV_AUX_OPEN_FAILED;
301 		return (EINVAL);
302 	}
303 
304 	/*
305 	 * Determine the device's minimum transfer size.
306 	 * If the ioctl isn't supported, assume DEV_BSIZE.
307 	 */
308 	if (ldi_ioctl(dvd->vd_lh, DKIOCGMEDIAINFOEXT, (intptr_t)&dkmext,
309 	    FKIOCTL, kcred, NULL) != 0)
310 		dkmext.dki_pbsize = DEV_BSIZE;
311 
312 	*ashift = highbit(MAX(dkmext.dki_pbsize, SPA_MINBLOCKSIZE)) - 1;
313 
314 	if (vd->vdev_wholedisk == 1) {
315 		uint64_t capacity = dkmext.dki_capacity - 1;
316 		uint64_t blksz = dkmext.dki_lbsize;
317 		int wce = 1;
318 
319 		/*
320 		 * If we own the whole disk, try to enable disk write caching.
321 		 * We ignore errors because it's OK if we can't do it.
322 		 */
323 		(void) ldi_ioctl(dvd->vd_lh, DKIOCSETWCE, (intptr_t)&wce,
324 		    FKIOCTL, kcred, NULL);
325 
326 		*max_psize = *psize + vdev_disk_get_space(vd, capacity, blksz);
327 		zfs_dbgmsg("capacity change: vdev %s, psize %llu, "
328 		    "max_psize %llu", vd->vdev_path, *psize, *max_psize);
329 	} else {
330 		*max_psize = *psize;
331 	}
332 
333 	/*
334 	 * Clear the nowritecache bit, so that on a vdev_reopen() we will
335 	 * try again.
336 	 */
337 	vd->vdev_nowritecache = B_FALSE;
338 
339 	return (0);
340 }
341 
342 static void
343 vdev_disk_close(vdev_t *vd)
344 {
345 	vdev_disk_t *dvd = vd->vdev_tsd;
346 
347 	if (vd->vdev_reopening || dvd == NULL)
348 		return;
349 
350 	if (dvd->vd_minor != NULL)
351 		ddi_devid_str_free(dvd->vd_minor);
352 
353 	if (dvd->vd_devid != NULL)
354 		ddi_devid_free(dvd->vd_devid);
355 
356 	if (dvd->vd_lh != NULL)
357 		(void) ldi_close(dvd->vd_lh, spa_mode(vd->vdev_spa), kcred);
358 
359 	vd->vdev_delayed_close = B_FALSE;
360 	kmem_free(dvd, sizeof (vdev_disk_t));
361 	vd->vdev_tsd = NULL;
362 }
363 
364 int
365 vdev_disk_physio(ldi_handle_t vd_lh, caddr_t data, size_t size,
366     uint64_t offset, int flags)
367 {
368 	buf_t *bp;
369 	int error = 0;
370 
371 	if (vd_lh == NULL)
372 		return (EINVAL);
373 
374 	ASSERT(flags & B_READ || flags & B_WRITE);
375 
376 	bp = getrbuf(KM_SLEEP);
377 	bp->b_flags = flags | B_BUSY | B_NOCACHE | B_FAILFAST;
378 	bp->b_bcount = size;
379 	bp->b_un.b_addr = (void *)data;
380 	bp->b_lblkno = lbtodb(offset);
381 	bp->b_bufsize = size;
382 
383 	error = ldi_strategy(vd_lh, bp);
384 	ASSERT(error == 0);
385 	if ((error = biowait(bp)) == 0 && bp->b_resid != 0)
386 		error = EIO;
387 	freerbuf(bp);
388 
389 	return (error);
390 }
391 
392 static void
393 vdev_disk_io_intr(buf_t *bp)
394 {
395 	vdev_buf_t *vb = (vdev_buf_t *)bp;
396 	zio_t *zio = vb->vb_io;
397 
398 	/*
399 	 * The rest of the zio stack only deals with EIO, ECKSUM, and ENXIO.
400 	 * Rather than teach the rest of the stack about other error
401 	 * possibilities (EFAULT, etc), we normalize the error value here.
402 	 */
403 	zio->io_error = (geterror(bp) != 0 ? EIO : 0);
404 
405 	if (zio->io_error == 0 && bp->b_resid != 0)
406 		zio->io_error = EIO;
407 
408 	kmem_free(vb, sizeof (vdev_buf_t));
409 
410 	zio_interrupt(zio);
411 }
412 
413 static void
414 vdev_disk_ioctl_free(zio_t *zio)
415 {
416 	kmem_free(zio->io_vsd, sizeof (struct dk_callback));
417 }
418 
419 static const zio_vsd_ops_t vdev_disk_vsd_ops = {
420 	vdev_disk_ioctl_free,
421 	zio_vsd_default_cksum_report
422 };
423 
424 static void
425 vdev_disk_ioctl_done(void *zio_arg, int error)
426 {
427 	zio_t *zio = zio_arg;
428 
429 	zio->io_error = error;
430 
431 	zio_interrupt(zio);
432 }
433 
434 static int
435 vdev_disk_io_start(zio_t *zio)
436 {
437 	vdev_t *vd = zio->io_vd;
438 	vdev_disk_t *dvd = vd->vdev_tsd;
439 	vdev_buf_t *vb;
440 	struct dk_callback *dkc;
441 	buf_t *bp;
442 	int error;
443 
444 	if (zio->io_type == ZIO_TYPE_IOCTL) {
445 		/* XXPOLICY */
446 		if (!vdev_readable(vd)) {
447 			zio->io_error = ENXIO;
448 			return (ZIO_PIPELINE_CONTINUE);
449 		}
450 
451 		switch (zio->io_cmd) {
452 
453 		case DKIOCFLUSHWRITECACHE:
454 
455 			if (zfs_nocacheflush)
456 				break;
457 
458 			if (vd->vdev_nowritecache) {
459 				zio->io_error = ENOTSUP;
460 				break;
461 			}
462 
463 			zio->io_vsd = dkc = kmem_alloc(sizeof (*dkc), KM_SLEEP);
464 			zio->io_vsd_ops = &vdev_disk_vsd_ops;
465 
466 			dkc->dkc_callback = vdev_disk_ioctl_done;
467 			dkc->dkc_flag = FLUSH_VOLATILE;
468 			dkc->dkc_cookie = zio;
469 
470 			error = ldi_ioctl(dvd->vd_lh, zio->io_cmd,
471 			    (uintptr_t)dkc, FKIOCTL, kcred, NULL);
472 
473 			if (error == 0) {
474 				/*
475 				 * The ioctl will be done asychronously,
476 				 * and will call vdev_disk_ioctl_done()
477 				 * upon completion.
478 				 */
479 				return (ZIO_PIPELINE_STOP);
480 			}
481 
482 			if (error == ENOTSUP || error == ENOTTY) {
483 				/*
484 				 * If we get ENOTSUP or ENOTTY, we know that
485 				 * no future attempts will ever succeed.
486 				 * In this case we set a persistent bit so
487 				 * that we don't bother with the ioctl in the
488 				 * future.
489 				 */
490 				vd->vdev_nowritecache = B_TRUE;
491 			}
492 			zio->io_error = error;
493 
494 			break;
495 
496 		default:
497 			zio->io_error = ENOTSUP;
498 		}
499 
500 		return (ZIO_PIPELINE_CONTINUE);
501 	}
502 
503 	vb = kmem_alloc(sizeof (vdev_buf_t), KM_SLEEP);
504 
505 	vb->vb_io = zio;
506 	bp = &vb->vb_buf;
507 
508 	bioinit(bp);
509 	bp->b_flags = B_BUSY | B_NOCACHE |
510 	    (zio->io_type == ZIO_TYPE_READ ? B_READ : B_WRITE);
511 	if (!(zio->io_flags & (ZIO_FLAG_IO_RETRY | ZIO_FLAG_TRYHARD)))
512 		bp->b_flags |= B_FAILFAST;
513 	bp->b_bcount = zio->io_size;
514 	bp->b_un.b_addr = zio->io_data;
515 	bp->b_lblkno = lbtodb(zio->io_offset);
516 	bp->b_bufsize = zio->io_size;
517 	bp->b_iodone = (int (*)())vdev_disk_io_intr;
518 
519 	/* ldi_strategy() will return non-zero only on programming errors */
520 	VERIFY(ldi_strategy(dvd->vd_lh, bp) == 0);
521 
522 	return (ZIO_PIPELINE_STOP);
523 }
524 
525 static void
526 vdev_disk_io_done(zio_t *zio)
527 {
528 	vdev_t *vd = zio->io_vd;
529 
530 	/*
531 	 * If the device returned EIO, then attempt a DKIOCSTATE ioctl to see if
532 	 * the device has been removed.  If this is the case, then we trigger an
533 	 * asynchronous removal of the device. Otherwise, probe the device and
534 	 * make sure it's still accessible.
535 	 */
536 	if (zio->io_error == EIO && !vd->vdev_remove_wanted) {
537 		vdev_disk_t *dvd = vd->vdev_tsd;
538 		int state = DKIO_NONE;
539 
540 		if (ldi_ioctl(dvd->vd_lh, DKIOCSTATE, (intptr_t)&state,
541 		    FKIOCTL, kcred, NULL) == 0 && state != DKIO_INSERTED) {
542 			/*
543 			 * We post the resource as soon as possible, instead of
544 			 * when the async removal actually happens, because the
545 			 * DE is using this information to discard previous I/O
546 			 * errors.
547 			 */
548 			zfs_post_remove(zio->io_spa, vd);
549 			vd->vdev_remove_wanted = B_TRUE;
550 			spa_async_request(zio->io_spa, SPA_ASYNC_REMOVE);
551 		} else if (!vd->vdev_delayed_close) {
552 			vd->vdev_delayed_close = B_TRUE;
553 		}
554 	}
555 }
556 
557 vdev_ops_t vdev_disk_ops = {
558 	vdev_disk_open,
559 	vdev_disk_close,
560 	vdev_default_asize,
561 	vdev_disk_io_start,
562 	vdev_disk_io_done,
563 	NULL,
564 	vdev_disk_hold,
565 	vdev_disk_rele,
566 	VDEV_TYPE_DISK,		/* name of this vdev type */
567 	B_TRUE			/* leaf vdev */
568 };
569 
570 /*
571  * Given the root disk device devid or pathname, read the label from
572  * the device, and construct a configuration nvlist.
573  */
574 int
575 vdev_disk_read_rootlabel(char *devpath, char *devid, nvlist_t **config)
576 {
577 	ldi_handle_t vd_lh;
578 	vdev_label_t *label;
579 	uint64_t s, size;
580 	int l;
581 	ddi_devid_t tmpdevid;
582 	int error = -1;
583 	char *minor_name;
584 
585 	/*
586 	 * Read the device label and build the nvlist.
587 	 */
588 	if (devid != NULL && ddi_devid_str_decode(devid, &tmpdevid,
589 	    &minor_name) == 0) {
590 		error = ldi_open_by_devid(tmpdevid, minor_name,
591 		    FREAD, kcred, &vd_lh, zfs_li);
592 		ddi_devid_free(tmpdevid);
593 		ddi_devid_str_free(minor_name);
594 	}
595 
596 	if (error && (error = ldi_open_by_name(devpath, FREAD, kcred, &vd_lh,
597 	    zfs_li)))
598 		return (error);
599 
600 	if (ldi_get_size(vd_lh, &s)) {
601 		(void) ldi_close(vd_lh, FREAD, kcred);
602 		return (EIO);
603 	}
604 
605 	size = P2ALIGN_TYPED(s, sizeof (vdev_label_t), uint64_t);
606 	label = kmem_alloc(sizeof (vdev_label_t), KM_SLEEP);
607 
608 	*config = NULL;
609 	for (l = 0; l < VDEV_LABELS; l++) {
610 		uint64_t offset, state, txg = 0;
611 
612 		/* read vdev label */
613 		offset = vdev_label_offset(size, l, 0);
614 		if (vdev_disk_physio(vd_lh, (caddr_t)label,
615 		    VDEV_SKIP_SIZE + VDEV_PHYS_SIZE, offset, B_READ) != 0)
616 			continue;
617 
618 		if (nvlist_unpack(label->vl_vdev_phys.vp_nvlist,
619 		    sizeof (label->vl_vdev_phys.vp_nvlist), config, 0) != 0) {
620 			*config = NULL;
621 			continue;
622 		}
623 
624 		if (nvlist_lookup_uint64(*config, ZPOOL_CONFIG_POOL_STATE,
625 		    &state) != 0 || state >= POOL_STATE_DESTROYED) {
626 			nvlist_free(*config);
627 			*config = NULL;
628 			continue;
629 		}
630 
631 		if (nvlist_lookup_uint64(*config, ZPOOL_CONFIG_POOL_TXG,
632 		    &txg) != 0 || txg == 0) {
633 			nvlist_free(*config);
634 			*config = NULL;
635 			continue;
636 		}
637 
638 		break;
639 	}
640 
641 	kmem_free(label, sizeof (vdev_label_t));
642 	(void) ldi_close(vd_lh, FREAD, kcred);
643 	if (*config == NULL)
644 		error = EIDRM;
645 
646 	return (error);
647 }
648